Re: Summary of the Multi-Path BOF at OLS and future directions

["Josef Möllers" <josef.moellers@fujitsu-siemens.com>]

Christoph Hellwig wrote:

> > 4. Configuration of this solution would be extremely important.  The
> > idea here is to rely on the udev solution currently making its way into
> > the kernel and essentially have a vendor specific multi-path
> > configuration as a udev plug-in.
> >
> > 5. Vendor value add for specific devices could be encoded both as
> > configuration (udev) pieces and plug-ins to the upper layer multi-path
> > driver to activate any proprietary vendor specific configuration options
> > that may be needed for specific solutions.
> 
> What are examples of such value add?

Some older EMC RAID boxes need a special "TRESPASS" command (implemented
as a MODE SELECT) to switch the ownership of a LUN from one path
("Storage Processor") to the other. The newer ones do this
automatically, though.
Without the TRESPASS, you'd see the LUN (INQUIRY), but you can't do
anything with it, even a simple READ CAPACITY fails.
-- 
Josef Möllers (Pinguinpfleger bei FSC)
	If failure had no penalty success would not be a prize
						-- T.  Pratchett
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